HIV post-exposure prophylaxis

What it is

Post exposure prophylaxis is what is given after exposure to HIV. It stands alongside pre-exposure prophylaxis, which is offered before exposure and together with counseling.

Pre-exposure prophylaxis is offered to three groups: people whose background incidence is above 2%, people with a recent STI diagnosis, and IVDU with sharing of needles. What is offered before exposure is emtricitabine and tenofovir, with counseling.

Who is eligible: the four criteria

Individuals are eligible for HIV PEP if four criteria are met, and the source cited for them is the MOH, Department of Communicable Diseases, HIV management in Oman, 3ed edition 2015.

1. Exposure occurred within the past 72 hours. PEP is more effective when given within the first 72 hours following exposure, and a first dose of PEP drugs, a starter dose, should be made readily available to potentially exposed individuals.
2. The potentially exposed individual is not infected or not known to be infected with HIV. HIV infection of the exposed person should first be ruled out by using rapid testing. However, an HIV test should NOT be a condition for initiating PEP, nor should PEP be delayed until the results of an HIV test become available, unless rapid testing is used.
3. Mucous membrane or non-intact skin was significantly exposed to a potentially infected body fluid.
4. The source is HIV-infected or the HIV status is unknown.

The fourth criterion is the one that answers the common question. An unknown source does not stop PEP; it is one of the two ways the criterion is met. In the worked case the exposure is within 72 hours, the doctor was screened but is not known to have HIV previously and PEP is not delayed waiting for the result, the exposure is significant, and the source is HIV unknown as yet, so PEP is started immediately and the result is not awaited.